I just bought the book today, so this hasn't been play tested in ACKS, but this has been my house rule for Classic for many years. I don't see why it wouldn't work.
I have re-named the Saving Throw categories simply to make them more generally applicable and easily understood by players. It's a lot more obvious which save applies in novel situations. I don't make any changes to the advancement tables, this is simply for the player's (and my) benefit of understanding. Each save is modified by something, but not always a stat.
Poison/Death - Fortitude (Con) - Pretty much the same as 3e.
Paralysis - Grapple (Str) - For anything you're trying to bust out of. Like pythons eating you. Still includes fighting off paralysis and petrification.
Breath Weapon - Block (Shield) - For any "Incoming!" you can deflect/block. Like a hail of darts or an explosion. Cover also modifies.
Wands, Staves - Dodge (Dex) - For any incoming attack you can't block. Like laser beams or falling boulders.
Spell - Mind (Chr) - All attacks to the mind/soul (no difference), from telepathy, to Magic Jar to psionics.
This book is a great addition to the ACKS system, as well as any OSR game, for much of the material in here could be easily ported to another game of choice. If you are running ACKS, this book will help tailor make the system to your world. If you are on the fence about ACKS, check this book out. Its flexibility and substance just might make you a convert.
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